Guava is known to have antiamebic, antibiotic, antidiarrheic, antihyperglycemic, antimutagenic, antispasmodic, and sedative effects, as well as anticough and narcotic-like activities of the plant species.

Take a handful of fresh guava leaves and rinse them in clean water. Chop the leaves. Boil them in about two cups of water with a pinch of salt, strain and cool. You can keep the leaves in the water for hours ahead of drinking. The medicine is stronger if the leaves are allowed to soak into the tea for several hours. Drink half a cup every three hours as needed for diarrhea. This will slow the diarrhea down and give you more energy.

Medicine for constipation: Ripe guava can be eaten when you are constipated to help you have a bowel movement.

Medicine for toothache: When you have a toothache or painful gums, you can place washed leaves in your mouth on the sore spot. Chew the leaf a little bit to release the medicine into the painful tooth or gum.

Medicine for Cataracts: Quercetin which is an antioxidant that blocks enzymes that are responsible for building sorbitol, the sugar that forms the cloudy white clusters that cause cataracts.

Other Medicinal uses: Guava leaves decoction is recognized for its effectiveness to cure several ailments, including the treatment of uterine hemorrhage, swollenness of the legs and other parts of the body, of chronic diarrhea, and gastroenteritis, among others. The most common use of the leaves is for cleaning and disinfecting wounds by rinsing the afflicted area with a decoction of the leaves. In the same way, such leaves are being used to aid in the treatment of dysentery and the inflammation of the kidneys. The bark and leaves can be used as astringent. It can also be used as a wash for uterine and vaginal problems, and is good for ulcers.